Halvorson declared herself “the only candidate who could avoid freshman orientation and hit the ground running,” in a statement to local reporters Monday morning.

Jackson announced his resignation from Congress last week amid reports that he had negotiated a deal with federal investigators for alleged campaign fund misuse.

Gov. Pat Quinn, a Democrat, had not scheduled a date yet for the special election in the heavily Democratic 2nd District in southern Chicagoland. Illinois election law states Quinn must schedule it within 115 days of the Congressional vacancy.

The field is expected to be crowded. Other potential candidates include Cook County Chief Administrative Officer Robin Kelly, state Sens. Toi Hutchinson and Napoleon Harris, plus Alderman Anthony Beale.

Halvorson lost her primary challenge to Jackson in March by a wide margin. The two Democrats sparred for years over a potential third airport south of Chicago — one of Jackson’s pet projects in Congress.

A longtime state lawmaker, Halvorson won a single term in Congress in 2008. She lost re-election in 2010 to Republican Rep. Adam Kinzinger.